[PATCH] staging: comedi: clarify/unify macros for NI macro-defined terminals

[Ian Abbott]

On 24/10/18 15:33, Spencer E. Olson wrote:
> Uses a single macro to define multiple macros that represent a series of
> terminals for NI devices.  This patch also redefines NI_MAX_COUNTERS as the
> maximum number of counters possible on NI devices (instead of the maximum
> index of the counters).  This was a little confusing and caused a bug in
> commit 347e244884c3b ("staging: comedi: tio: implement global tio/ctr routing")
> when setting/reading registers for counter terminals.
> 
> Fixes: 347e244884c3b ("staging: comedi: tio: implement global tio/ctr routing")
> Signed-off-by: Spencer E. Olson <olsonse at umich.edu>
> ---
>   drivers/staging/comedi/comedi.h | 39 ++++++++++++++++++---------------
>   1 file changed, 21 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
> index e90b17775284..09a940066c0e 100644
> --- a/drivers/staging/comedi/comedi.h
> +++ b/drivers/staging/comedi/comedi.h
> @@ -1005,35 +1005,38 @@ enum i8254_mode {
>    * and INSN_DEVICE_CONFIG_GET_ROUTES.
>    */
>   #define NI_NAMES_BASE	0x8000u
> +
> +#define _TERM_N(base, n, x)	((base) + ((x) & ((n) - 1)))
> +
>   /*
>    * not necessarily all allowed 64 PFIs are valid--certainly not for all devices
>    */
> -#define NI_PFI(x)	(NI_NAMES_BASE        + ((x) & 0x3f))
> +#define NI_PFI(x)		_TERM_N(NI_NAMES_BASE, 64, x)
>   /* 8 trigger lines by standard, Some devices cannot talk to all eight. */
> -#define TRIGGER_LINE(x)	(NI_PFI(-1)       + 1 + ((x) & 0x7))
> +#define TRIGGER_LINE(x)		_TERM_N(NI_PFI(-1) + 1, 8, x)
>   /* 4 RTSI shared MUXes to route signals to/from TRIGGER_LINES on NI hardware */
> -#define NI_RTSI_BRD(x)	(TRIGGER_LINE(-1) + 1 + ((x) & 0x3))
> +#define NI_RTSI_BRD(x)		_TERM_N(TRIGGER_LINE(-1) + 1, 4, x)
>   
>   /* *** Counter/timer names : 8 counters max *** */
> -#define NI_COUNTER_NAMES_BASE  (NI_RTSI_BRD(-1)  + 1)
> -#define NI_MAX_COUNTERS	       7
> -#define NI_CtrSource(x)	       (NI_COUNTER_NAMES_BASE + ((x) & NI_MAX_COUNTERS))
> +#define NI_MAX_COUNTERS		8
> +#define NI_COUNTER_NAMES_BASE	(NI_RTSI_BRD(-1)  + 1)
> +#define NI_CtrSource(x)	      _TERM_N(NI_COUNTER_NAMES_BASE, NI_MAX_COUNTERS, x)
>   /* Gate, Aux, A,B,Z are all treated, at times as gates */
> -#define NI_GATES_NAMES_BASE    (NI_CtrSource(-1) + 1)
> -#define NI_CtrGate(x)	       (NI_GATES_NAMES_BASE   + ((x) & NI_MAX_COUNTERS))
> -#define NI_CtrAux(x)	       (NI_CtrGate(-1)   + 1  + ((x) & NI_MAX_COUNTERS))
> -#define NI_CtrA(x)	       (NI_CtrAux(-1)    + 1  + ((x) & NI_MAX_COUNTERS))
> -#define NI_CtrB(x)	       (NI_CtrA(-1)      + 1  + ((x) & NI_MAX_COUNTERS))
> -#define NI_CtrZ(x)	       (NI_CtrB(-1)      + 1  + ((x) & NI_MAX_COUNTERS))
> -#define NI_GATES_NAMES_MAX     NI_CtrZ(-1)
> -#define NI_CtrArmStartTrigger(x) (NI_CtrZ(-1)    + 1  + ((x) & NI_MAX_COUNTERS))
> +#define NI_GATES_NAMES_BASE	(NI_CtrSource(-1) + 1)
> +#define NI_CtrGate(x)		_TERM_N(NI_GATES_NAMES_BASE, NI_MAX_COUNTERS, x)
> +#define NI_CtrAux(x)		_TERM_N(NI_CtrGate(-1)  + 1, NI_MAX_COUNTERS, x)
> +#define NI_CtrA(x)		_TERM_N(NI_CtrAux(-1)   + 1, NI_MAX_COUNTERS, x)
> +#define NI_CtrB(x)		_TERM_N(NI_CtrA(-1)     + 1, NI_MAX_COUNTERS, x)
> +#define NI_CtrZ(x)		_TERM_N(NI_CtrB(-1)     + 1, NI_MAX_COUNTERS, x)
> +#define NI_GATES_NAMES_MAX	NI_CtrZ(-1)
> +#define NI_CtrArmStartTrigger(x) _TERM_N(NI_CtrZ(-1)    + 1, NI_MAX_COUNTERS, x)
>   #define NI_CtrInternalOutput(x) \
> -		     (NI_CtrArmStartTrigger(-1)  + 1  + ((x) & NI_MAX_COUNTERS))
> +		      _TERM_N(NI_CtrArmStartTrigger(-1) + 1, NI_MAX_COUNTERS, x)
>   /** external pin(s) labeled conveniently as Ctr<i>Out. */
> -#define NI_CtrOut(x)  (NI_CtrInternalOutput(-1)  + 1  + ((x) & NI_MAX_COUNTERS))
> +#define NI_CtrOut(x)   _TERM_N(NI_CtrInternalOutput(-1) + 1, NI_MAX_COUNTERS, x)
>   /** For Buffered sampling of ctr -- x series capability. */
> -#define NI_CtrSampleClock(x)	(NI_CtrOut(-1)   + 1  + ((x) & NI_MAX_COUNTERS))
> -#define NI_COUNTER_NAMES_MAX   NI_CtrSampleClock(-1)
> +#define NI_CtrSampleClock(x)	_TERM_N(NI_CtrOut(-1)   + 1, NI_MAX_COUNTERS, x)
> +#define NI_COUNTER_NAMES_MAX	NI_CtrSampleClock(-1)
>   
>   enum ni_common_signal_names {
>   	/* PXI_Star: this is a non-NI-specific signal */
> 

It's no more ugly than the original, although I pity the fool who has to 
make sense of the preprocessor output!

Reviewed-by: Ian Abbott <abbotti at mev.co.uk>

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